We should also keep a track of folks and vids of some 'custom' setups. I have my MadDad midpipes hanging around off my 135i, and was planning on slapping them on the 1///M. The HPA car is running an aftermarket midpipe on stock exhaust too (Berk IIRC) and I recall the guys commenting it sounded sweet.
PS: That last clip of the Akra on the street car is darn loud!
2011 BMW E82 1///M: AW, ZPP+ZCV, HK, Apps; Akra CF+Valve control, MadDad mids, K&N, Forge FMIC, P3gauge, EuroTails, Tint, CF Mirrors+Spoiler+Roof+RevoZ diffuser, 10mm H&R, IND grills+gills, xCDV, LUX AE
2008 Audi B7 RS 4: Sprint Blue, Audi Exclusive Euro Interior, Premium+Titanium Package, EPL Tune, Stasis Ohlins MS coilovers, Milltek valved exhaust+DownPipes, Stoptech lines, Tint, ADR V1, Lidatek, Lamin-X, Strasse Forged SM7 3-piece concave wheels, 275/30/19 PSSs, Euro flat-bottom steering wheel, JHM SSK